Emily Sullivan

Hawaii residents and tourists alike were shaken shortly after 8 a.m. local time Saturday when a push notification alerted those in the state to a missile threat, causing an immediate panic until officials confirmed it was a false alarm.

"BALLISTIC MISSILE THREAT INBOUND TO HAWAII. SEEK IMMEDIATE SHELTER. THIS IS NOT A DRILL," read the message, which also blared across Hawaiian televisions stations.

The death toll rose to 20 on Sunday as authorities ramped up search and rescue efforts for those missing in the deadly mudslides in Santa Barbara, Calif. And hope of finding the four remaining missing persons alive, five days after storm devastated the region, is vanishing.